<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    .active {
      color: red;
    }
  </style>
</head>

<body>

  <div id="app">
    <!-- <h2 class="active">{{message}}</h2> -->
    <!-- <h2 :class="active">{{message}}</h2> -->

    <!-- <h2 v-bind:class="{key1: value1, key2: value2}">{{message}}</h2> -->
    <h2 v-bind:class="{active: isActive, line: isLine}">{{message}}</h2>
    <h2 v-bind:class="getClasses()">{{message}}</h2>
    <button v-on:click="btnClick">按钮</button>
  </div>

  <script src="../js/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        message: 'Hello',
        isActive: true,
        isLine: true
      },
      methods: {
        btnClick: function () {
          this.isActive = !this.isActive
        },
        getClasses: function () {
          return { active: this.isActive, line: this.isLine }
        }
      }
    })
  </script>

</body>

</html>